Multiple channel electro-optical system



W. A. KNOOP June 11, 1940.

OPTICAL SYSTEM MULTIFLE' CHANNEL ELECTRO- Filed Dec. 24, 1956 2 Sheets-Sheet 1 QQNN QQNN QQNN INVENTOR W. A. KNOOP BY ATTORNEY June 11, 1940.-

W. A. KNOOP MULTIPLE CHANNELELECTRO-OPTICAL SYSTEM Filed Dec. 24, 1936 2 Sheets-Sheet 2 flvvnvrm WA. KNOOP A r Tom/E 1 Patented June 11, 19403 MULTIPLE CHANNEL ELECTRO- OPTICAL SYSTEM 1 v William Knoop; Hempstead, N. Y., assignor to e Bell Telephone Laboratories, Incorporated,

New York, N. ;Y., a. corporation of New York Application December 24, 1936, Serial No. 117,530

8 Claims, (01. ids-5.2)

' r This invention relatestoflelectro optical systems for the transmission "and production of images preferably in their natural colors and more particularly to a method and means for reducing extraneouspatterns in-the image field due to scanning strip-by-stripi t An object of this invention is to provide an improved television imageproducing'system employing overlapping lines.

Another object is to increase the flicker frequency of the formed image above that annoying tothe observer withoutincreasing the picture or irnagefrequency. I

Another object is toincrease at the receiver the ll number of lines across the field of View over that of the definition or fundamental number of scanning lines by a multiplier equal to the number of primary colors, by opticallysuperimposing/the primary color image fields with the respective scanning lines of each proportionately displaced and overlapping a fraction of the width of a scanning line, in combination with the staggering of the scanning lines of alternate scanning cycles.

A further objectof this invention is the pro vision of means for scanning Kodacolor film so that the resultant color component signals,

employed at the receiverto produce an image in color, have a substantial reduction in transmissionband width as compared to that for the usual monochrome pictures of the samefineness of structure. s I

p A feature of this inventionis the simultaneous production of a plurality of photoelectric signal currents for the respective images of each pri- 36 lllaly color component of the object or picture qwhose image is to be transmitted by meansof a singlesca nning aperture operating'at each inl stant in thescanning plajneand causing a multiple production of signal currents which may be readily adapted at the receiver to simultaneously superimpose a corresponding plurality of images with the respective scanning lines concurrently produced displaced by a desired amount, particularly by an amount :to cause a separation of the lines simultaneously being scanned substantially equal to the heightof the field of view divided by the number of images being simultaneously formed and plus or minus a fraction of the width of a scanning lineto cause an overlapping ofthe lines.- The scanning foreach color component is preferably such that the scanning covers the entire image field. v

Electro-optically produced images formed by scanning juxtapositioned lines of' a field of 'vieW maybe given an improved appearance either by increasing the resolution by the simple method of increasing the number of fundamental scanning lines; or by increasing thepicture flicker frequency up to a point where the persistence of vision holds the image in the eye with practically no fading, without increasing the resolution by the first-mentioned method. Flicker frequencies of the order of 35 flashes per second with moderate intensity of illumination, and 48 flashes per second with higher values of illumination, are sufficient and going higher is of no avail as the eye does does not consciously detectfli cker beyond this range. The latter plan while theoretically perhaps not as desirable as the formerthas the practical advantage of requiring a lower total frequency bandfor transmission, since the signal frequency increases as the square of the number of scanning lines in the former plan and at approximately one-half to tWOr-thlrdS this rate in the latterplan where the fundamental number of scanning linesis kept relatively low and the appearance of the produced image is equally good in both cases. This invention is directed to;the latter arrangement. n l 1 r In the specific system of threecolor television herein disclosed by way of example the three color components of a 48 line field are each optically rate of 16 frames per second will cause a flicker frequency of 4 8flashes per second, which is ;or'- dinarily practically unobservable to the eye. Forty-eight flashes per second is the frequency of good commercial projection of motion pictures wherein 24 picture frames are projected persec 0nd and each is exposed two times per frame by the operationof the shutter. 1 n

In electro-optical transmission; the transmis sion frequency band Width in the above example of 48 fundamental picture lines for the three color components, each scanned at the rate of 16 per second and with a flicker frequency of 48 flashes per second,:the total transmission frequency band equals 1 I l 48 16 3 n 2 n or 55,296 cycles per second. With ordinary monochrome scanning, this rate of 16 frames per secondis too low because the flicker becomes objectionable. Even taking the motion picture rate of 24 frames per second, scanned two times per exposure by the ordinary scanning arrangement, the flicker frequency is 24x2 or 48 flashes per second and the total transmission frequency is or 55,296 cycles per second, but although the flicker frequency is maintained the same, the quality of the produced image becomes greatly impaired by reducing the apparent line structure to 48 lines, or at most to 96 if stagger scanning is employed, as compared to 288 lines. However, a flicker frequency of 48 is appreciably higher than needed and if the fundamental picture scanning rate is reduced to 12 frames per second the flicker frequency is 36 flashes per second and the total transmission frequency band is reduced to the two sets radially displaced by one-half the Width of a scanning line and each set successively angularly positioned 180 degrees around the scanning disc. The two sets of apertures thus arranged shift the fundamental scanning lines of alternate scanning cycles by one-half the width of a line and thus double the apparent number of scanning lines with a consequent reduction of the appearance of line structure. The preferred arrangement is such that the disc scans moving images produced from a continuously moving Kodacolor film, one frame of the filmpassing the field of view as each set of apertures passes through its scanning cycle. With continuous uniform movement of the film, the scanning apertures are circularly arranged. While the scanning lines for a single frame are not staggered by the apertures in the scanning disc, the scanning lines of alternate frames are staggered with respect to each other by onehalf a line width. A further shifting or staggering of the scanning lines as heretofore mentioned is brought about by the optical system. This second relative shifting is between the different respective primary color component images and is in addition to the first.

The respective color component images formed at the transmitter in the scanning plane from the Kodacolor film, comprise the color components preferably of the three primary color images, respectively. The scanning path is transverse to the lenticular structure and to the longitudinal movement of the film. The lenticular structure of the Kodacolor film directs the light from the color records to respective portions of the projectionv lens corresponding to the three primary color components. It is, therefore,possib1e to optically separately channelize the light rays which form the color component images, and cause the concurrent energization of the color component channels or paths.

of three separate photoelectric cells, each arranged or positioned to pick up the light of a single color component channel. With the arrangement so far described, the staggering or shifting of the scanning lines is effected entirely by the physical position or relative displacement of the two sets of scanning apertures in the transmitter scanning disc. The second or op tically produced stagger is brought about by optically relatively shifting by a proportionate fraction of a scanning line or multiple thereof the three images formed from the respective primary color components. This is accomplished by positioning two optical deviating elements such as prisms in the light path, in the optical position of the usual color filters, between the Kodacolor film and the scanning disc in two The third color component light path need not be deviated. One prism causes a shift, say, of the blue light image components one-third the length of a projected picture frame less one-third the width of a scanning line in the direction of the movement of the image of the Kodacolor film in the scanning plane while the other prism causes a shift, say, of the red light image components, one-third the length of a projected picture frame plustwo-thirds the width of a scanning line in the direction opposite to the movement of .the

, image of the Kodacolor film, while the green imposed by approximately one-third of each frame. It is, of course, this center third that the scanning apertures successively pass in scanning so that the effective scanning aperture at any instant passes color components for each of the primary colors'simultaneously. This displace ing of the three respective primary color images by approximately one-third the frame length causes an image scanning phase displacement of approximately degrees. Other relative image displacements would cause scanning phase displacements of different amounts, for example, a displacement of one-sixth the length of a frame would cause a scanning phase displacement of 60 degrees. The amount of the displacement depends upon the scanning phase displacement desired informing the superimposed component images at the receiver. If two color component transmission were employed, the simplest proportional displacement would be of the order of approximately half the longitudinal length of aframe and the components would have a phase displacement of approximately degrees. This arrangement makes the transmitting scanning color film ,for the electro-optical transmission of pictures or images in natural color even more simple than the usual color processes of generating the several color component signal currents by the use of plain film or even the direct grees which are angularly displaced with respect havethe radial position of the respective apertures of each set so positioned that thescanning lines of each set proportionately overlap, each set scanning the entire field of viewfor the color components of one of the respective primary colors. The scanning lines are shifted, as already stated, in alternate scanning cycles by one-half the width of the scanning linesso as to further reduce the appearance ofline structure in the formed image. The shifting may be brought. about by opticalmeans such as arefracting element positioned in thescanning path which is moved at the. end of each revolution of the scanning discin a manner to cause alternate backandforth shifts of the. scanning beam. by half the width of ascanning line. Thisalternate. shift between scanning cyclescausing alstagger of the scanning lines. may also be very simply achieved by arranging two groups of spirally positionedapertures inopposite halves of a scanning disc so that the apertures in. onehalf of the disc cause three completescannings of the field of view. comprising one scanning for eachi of the three primary color components during one-half a revolution :of the scanning smaller disc.

.1 Three different primary respective scanning apertures or, the different primary color light sources may be attached to cycle. and that these. lines are relatively shifted proper apertures.

disc, and during the other half revolution of the scanning disc the apertures inthesecond. half of .the disc also causes onecomplete scanning for each of the three primary color components, but with. the j scanning lines of the alternate scanning cycles relatively staggered to cause a 50 per cent overlap of the scanning lines. responding apertures in the two halves of. the

scanning disc have a relative radial displacemechanical positioningof the .two groups of apertures in the scanning disc, the resulting scanning is the same. a The latter arrangement is illustrated in the drawing and subsequently described more in detail. While the disc in .the preferred arrangement is twice the diameter of .the disc having one. group of three spirals, it

is rotated atone-half the angular speed of the color component light sources are associated with the scanning disc at the receiver, onewith each plurality of scanning apertures representative of the different respective primary colors. The three color component light sources may be either stationary and have their light directed by optical means to their the scanning disc directly in alignment withthe The reduction of. line structure in the. production of the formedimage as already pointed out, is an important feature of this inventionand the fact that the field of view at the. receiver is scanned} simultaneously. for three overlapping lines representative. of each. of

the! primary color components in each scanning in each alternate scanning cycle produces an unusually fine line structure in the formed, image, In comparison with an ordinary monochrome.

imagewithout any line stagger, it ispbyious.

The corthat each scanning path is made up of proportionately overlapping components of the. three primary colors and they are shifted between alternate scanning cycles by one-half their width.-

The scanning arrangement at the receiver must, of course, match that at the transmitter. example, with each of the three color components comprising forty-eight overlapping lines, the apparent structure is three times 48 or 144 for a single scanning cycle and with the alternate shift, two times 144 or 288 as heretofore stated in the general description of the scanning arrangement.

A softening of 1 the scanning line structure by chromatic dispersion may be substituted for the slight shifting of the three lines of the three color. components. l Thismay be effected by a prism. positioned with its base parallel to the direction of scanning in front of the field of View.

A more detailed description of an embodiment chosen for illustrating this, invention follows:

Fig. 1. is a schematic plan view, partly in crosssection, of the transmitting scanning arrangement comprising a source of light, a Kodacolor film, a scanning disc, light sensitive cells and an optical system employed therewith, for simultaneously generating a plurality of photo electric currents; and the receiving scanning arrangement comprising. aplurality of sources of light which vary in intensity in accordance with received signal currents, a scanning disc member and an-optical system employedtherewith, for producing images.

Fig, 2 is a side elevation view, partlyin crosssection, of that portion of the transmitting apparatus of Fig. 1 atthe left of plane .r:r, showing -more particularly thefilm moving arrangefrom the foregoingthat this arrangement has .a line structure six times (as fine due to thefact For ment and the retracting elements or prisms in the optical system for. effecting image displacement in a vertical direction.

Fig. 2A is a diagram showing the relative positions of the red, green and blue images as projected in the, scanningplane at the transmitter.

Fig. 3 isa side elevation viewwith parts broken away of the receiving apparatus of Fig. 1 showing more particularly the opticalarrangement.

Fig. 3Aisfa vertical cross-section of a portion of the scanning disc assemblyandl the associated optical elements of the receivingapparatus.

Fig. 4 is a face view'of a transmitting scanning disc for use with continuously moving film showing the relative arrangement of two groups of circularly arranged scanning apertures.

Fig. 5 is a. diagram showing the overlapping scanning paths of the .two groups of scanning apertures in the transmitting scanning disc particularly illustrating the positioning of different shaped aperturessuch as round, square, and diamondeshaped apertures.

Fig.6 is a face view of a receiving scanning disc showing the relative arrangement of two groups of spirally arranged scanning apertures as used for producing images.

Fig. :7 isa diagram. showing the overlapping and an optical system employed therewith for simultaneously generatinga plurality of photo-- and an optical system employed therewith for producing images. .At the transmitter a finished motion picture film of the object whose image is to be transmitted, which maybe produced by the Kodacolor process or a film of similar type, namely, a film provided on one surface with a continuous series of longitudinal lenticular element, and, on its other surface with a photographic emulsion which has been exposed through a suitable lens system having associated therewith athree-color filter and afterwards developed in accordance with established methods. The image on the film appears as black and white but comprises a triple linear mosaic produced by the lenticular ridges on the. film. A source of light H has its rays directed by the condenser lens system Hi to the Kodacolor film |20which moves at a uniform rate past the aperture H3 in the opaque plate H2. This aperture subtends one picture frame of the film and the opaque plate shields the film. from superfluous light. The illuminating light after passing through the Kodacolor film I20 comprises threeparts corresponding to the respective colors of the filter through which the record on the film was made. The light next passes through the lens system I32 and 33 to the scanning disc M0. The film record of the three component images is accurately focussed in the plane of the scanning disc l Ml'by this lens system. Theseimages are formed in black White. The lens system I60 beyond the scanning disc produces in the apertures 16 IR, MIG and lSlB the image of the zones B, G and R in plane 36. The light passing through these Zones in plane 30 contains respectively the color components of the blue, green and red of the images on thewfilm. By thus imaging them the color components are again separatedafter'scanning. The lens system. it acts as a lens in the regular projector and the light after passing through the three apertures IBIR, "MG and IBIB is directed into the respective photoelectric cells by the assistance in two of the channels of the mirrors ISZR and lB2B. The light sensitive cells are all similar and obviously no color filters are employed at the transmitter. Color is used only at the receiver where the respective signal currents are used for producing images of the original object or scene in natural colors. Even color might be omitted at the receiver and the image produced in black and white tones. Asthe film preferably moves continuously at a uniform rate, the scanning apertures in the scanning disc I40 are circularly positioned as shown in detail in Fig. 4. As already explained preferably'two groups of apertures A and B are employed each occupying successive circular angular spaces of 180' degrees and the two groups Al ll and BN2 are-offset radially by one-half the width of scanning line in order to produce a stagger of the scanning lines in alternate scanning cycles. In the arrangement here shown thescanning disc andthe film are spaced some distance-from each other as this is preferable both optically and mechanically and more particularly when Kodacolor filmis used as it affords space for properly positioning the elements and for optical focussing. A modified and alternative arrangement maybe employed in which the film and scanning disc are adjacent depressed four and two-third lines.

to one another but this is undesirable mechanically, particularly since it would be-necessary for them'to be practically in contact. The preferred optical arrangement shown is similar to that used in regular projectors for Kodacolor film wherein the set of red, green and blue filters are positioned infront of the lens E32 and the image screen is positioned beyond at a suitable distance. In this scanning system at the transmitter both the filters and the screen are omitted and in IB'IB to deflect or refra'ct the blue components upward-1y while the greencomponents are allowed to pass directly without change of direction be tween these two prisms. the color components of the red, green and blue images are relatively displaced vertically on the scanning disc. This displacement is preferably equal to approximately one-third'the longitudinal dimension of a picture, the exact displacement in the illustrated, embodiment being such that the blue image: B is displaced, upwardly from the green image G one-third the longitudinal dimension of a picture lessone-third of a line while the red image R is displaced downwardly from the green image G one-third the longitudinal dimension ofapicture plus two-thirds of a line.

The scanning discs Figs. 4 and 6, which will be described later, are shown for scanning a twelve line picture since for a small number of lines the scanning arrangement may be more clearly illustrated in the drawings. In a twelve-line picture the blue image B is displaced upwardly with respect to the undeviated green image G by three and two-third lines and the red image R is These fractions result from the design of the receiving disc. and other arrangement of the receiving spirals will'result in a diilerentarrangementat the transmitter. A large number of combinations are possible all within the scope of this invention' In this way one scanning aperture at each instant is caused to scan three different parts of the picture simultaneously. If, at. a particular instant, the disc is scanning in the center third of the screen image, it is also scanning in the top' third of'the red image and in the bottom. third of cells. The three'image currents corresponding to a given white portion of the image will be With this arrangement.

their place are positioned two prisms lalR'and I |8lB in the zones of the red and blue com-- identioalin formand amplitude but will be dis- The scanning of a picture frame during its longitudinal movement across the scanning field is here considered as a full picture cycle of 360 degrees and it follows that one-third of a picture frame or cycle comprises 120 degrees of the picture cycle. The relative displacement longitudinally of the several images may be made any desired amount by adjusting the amount .of refraction caused by the two prisms I8IR and I8IB. However, a substantially proportionate relative displacement is preferable but this dis placement must correspond. to the system employed at the receiver for, producing the formed image. Three photoelectric cells I'IIR, IIIG and I'IIB activated by the red, green and blue light image components respectively generate three im-,

age currents which, after amplificationin amplifiers ISIR, I9IG and ISIB, are transmitted over. separate channels, 30I,3ll2 and 303 to a member employed therewith for producing images is schematically shown in. a plan view in the right portion of Fig. 1. The several signal currents received over channels 30I, 302 and 303 are regulated and amplifiedin amplifiers ZIOR;

; 2 IllGand 2 IE, respectively, and impressed upon light sources 220R, 220G and 2203, emitting light of the proper mixing proportions of the. three primary colors, respectively. Suitable color fil-, ters may be employed with the light sources; These light sources are associated with ascanning disc member 240 comprising a numberof discs, the details of which will be described later, so arranged with apertures and light baffle plates that each light source at any instant is illuminatingonly one respective elemental area on the field of view and causing a scanning of the field in accordance with the sequence heretofore de scribed. This scanning disc member is driven :by the motor 250 operated in synchronism. and in phase with the scanning disc at the transmitter by any well known means, the details of which are not here shown. An opaque apertured plate 28!! having an aperture 28I :defining the field of view or image area is positioned in .front of the scanning disc member to prevent any light other. than that passing through the active scanning apertures from being seenby observers. The ark rangement and relationship ofthe several light sources with the scanning disc memberis such that ,each light source preferably scans successive lines until the entire'area of the fieldhas been scanned. Thescanningzlines produced by the respective light sources at each instant are approximately 120 degrees apart and consequent- 1y scanning. is occurring ateachinstant in three separated regions of the image, the'respective scannings occurring in different thirds of the image field in a three channel system. Means for accomplishing this will be described more in detail in connection with Figs. 3, 3A, (i and 'l. g Fig. 2 shows .a side elevation view, partly in cross-section, of that portion. of the; transmitting apparatus of Fig. 1 at the left of plane :c--x showing more particularly the'film moving arrangement and retracting elements or prisms in theoptical system for effectingimage displacement in a vertical or longitudinal direction.

The description of Fig l relating-particularly to the optical system is applicable here The motor" I50which drives the scanning disc I40 also drives the film through a film driving gear u1iit-I5I. The film IZIIis carried on reels I52 and I53 and passes downwardlyover rollers I54 and I55 arranged to assist in guidingand driving it at a uniform rateacross the field of view. The lower roller I55 equipped with drive sprockets is connected by suitable gearing and the shaft I56 with the film driving unit I5I while the film receivingreel I53 is. also connected by pulleys and a slipable belt I51 to the driving unit for winding the used film upon the receiving reel all in accordance with well-known practice. Fig. 2 particularly shows the optical action of the refracting elementsfiror prisms. I8IR. and IBIB in relatively displacing the continuously moving image componentsiby directing, for example, the red image light components R downwardly and theblue image light components B upwardlywith respect to the green image light components G so as tocause the relative displacement of the three sets of image components on the scanning disc as already described. These retracting prisms are preferably achromatic to. avoid color fringes on the deviated images although for simplicity they are shown as simple prisms in the dravirings. A scanning apjerture AI-II is scanning an elemental area of each of thesuperimposed portions of the three primary color component images.

Fig. 12A shows diagrammatically the relative displacement and overlapping positions of the red, green and blue image components of a picture frame as projected on the scanning field at the scanning disc I40 at the moment when oneof the images, namely, the green image, is positio-nedjwith its centerin the center of the scanning field. As stated above, the relative displacement is caused by prisms IBIR and I8IB, and the red, green and blue image components R, G and B, are shown longitudinally or vertically positioned so that fora given picture frame the portions superimposed are approximately the top third of thered image components, the middle' thirdiof'the' green image components and thebottom third of the blue image; components.

, The exact relative displacement is such that the blue image components are displaced with respect'toithose of the green image one-third the length of a projected picture frame less onethird the width of'scanningfline in the direction of the movement of the image of the Kodacolor film while the red image components are displaced with respect to those of the green image one-third the length of a projected pioture frame plus two-thirds the width of a scannient of the image of the Kodacolor film. At

each instant one elemental area of the image field is scanned within the zone where a portion of the three images are superimposed upon one.

another such as along the path or line L.

The film I20'used at the transmitter for forming images 'to be scanned for generating the photoelectric currents may be stationary while being scanned and intermittently advanced bethe film frames are projected and stationarily superimposed on the image scanning field with the proper proportionate relative displacement during the scanning cycles. The groups of scanning aperturesin the scanning disc I40 are posining line in the direction opposite to the movetioned in spiral arrangement in accordance with the usual practice in: scanning a. fixed two-dimensional image field.

Fig. 3 shows a side elevation view with parts broken away of the receiving apparatus of which a plan view is shown in' Fig. l, and more particularly shows the relationship of the light sources with the scanning disc member and means for directing the light from. each light source at any instant through a respective aperture of the scanning disc passing the field of view..- The scanning disc member comprises a scanning disc 240 having two groups of spirally arranged scanning apertures. Each group. angularly extends 180degrees in the preferred arrangement. The relative positioning of the several spirals is shown in Fig. 6 which is subsequently described in detail. The apertures in the. disc are accurately positioned andcontrol' the movement of the scanning beams frcomv each of the three light sources 220R, 220G and 22013,

respectively. Light from the several sources is simultaneously directed in mutually exclusive channels formed in the spaces between successive pairs of discs 240, 24! 2'42 and 243 to prisms or mirrors Z'HR, ZHG and 2113' which change their directions approximately degrees and then through the proper apertures in the scan ning disc 2%. The light direction changing reflectors are mounted between the several discs and rotate therewith, one such deflector being employed for each scanning aperture. The apertures AZSIR, A2EIG and A26IB have associated therewith lightdirection changing" deflecting elements ,Z'HR, 211G and ZHB, respectively, while apertures B2523, B262G and B26233, have associated therewith deflectors 212B, 212G and 272R, respectively; In the drawings, for clarity, only two such deflectors are shown on each ofthethree supporting discs. The light sources should be of sufficient length to adequately span the angular or transverse width of the field of view, but their radial dimension may be small and as here shown, they are linear light sources. The light rays are shielded and directed asshown in their proper channels by' any suitable means and the image field of view is defined by the opening 2M in the stationary opaque plate 288 The light sources as here shown are stationary, but any other suitable arrangementfor channelizing the light from the several sources into mutually exclusive scanning beams may be used such as are shown in the patent issued to Blackwell and Herman, No. 2,101,976, dated Dec. 14, 1937, the chief difference in this" arrangement being the employment of color component sets of spirally shaped lamps in association with the proper spanning apertures in the scanning disc 240. I

Fig. 3A is a vertical cross-section of a portion of the scanning disc assembly and the associated optical elements in the receiving appara'tus showing more in detail the optical arrangement for directing the scanning light from the linear light sources through thescanning apertures in divergent beams so that the beam-sysubtend in passing the field of view sufiiciently wide angles to permit a number of persons to simultaneouslyview the produced image. This divergence of the scanning beams is obtained by associating with each aperture of the scanning disc 24183. a lens which is quite large in comparison with the size of the aperture and of comparatively short focal length. The image is viewed directly at the plane of the scanning disc by positioning the eyes of the observers. within the field common: to all ofv the cones of light passed through the scanning discwapertures within the area of the scanning field. The cross-section shown in Fig. 3A is normal to the face. of and coincides with the radius of the scanning disc passing through apertures AZEIR, A2BIG, and AEGIB. Light controlled by the signal currents in the several channels is. producedin the'stationary linear light sources 226R, 220G, and. 22GB; These light sources are of small cross-section and of sufficient' length to permitlight from; them to be. directed through each scanning aperture as it passes across the scanning field. Stationary collimating cylindrical lenses 238R, 2306, and 23GB, associated respectively with each of the stationary light sources,direct the light therefromin substantially parallel beams onto direction changing elements 211R, Z'HG and THE,

respectively, which change the direction of the beams approximately 90 degrees and causes them to impinge upon lenses, 260R, 268G and 266B, respectively, as their'associated apertures in the scanning disc 24!) pass the scanning field. The

direction changing elements ZHR, Z'HG- and Z'HB' are mounted on discs 24!, 2'32. and 243, respectively, and rotate with the scanning disc 2413.

One such light direction changing element is aligned with each aperture'in the scanning disc.

Certain openings about the size of the lenses associated' with the scanning disc apertures are formed in alignment therewith in the bafiie discs 24! and 242 for the passage of light from light sources 220G and 220B to: the scanning apertures in the scanning disc 240'. In the forward bafiie disc 24! two rows of openings are required as light from both light sources 229G and 22GB I formed with comparatively large holes at the aperture positions and an apertured member and lensassembly is placed'in each hole and firmly held therein. Asshown for aperture ZBIB this assembly consists ora'cup-shaped member 245 of thin opaque material which is pressed into the above-mentioned large hole at the position of aperture 26 IB and accurately drilled or punched to form the aperture, and lens 2503 with itsholding frame 246 is inserted in cup-shaped member 245 and held bythe tight-fitting holding ring 24?; The ring Z il maybe either pressed into place, or after being shrunk by cooling to 'a low temperature 'put in place and allowed to expand to a tight fit upon rising to normal term perature; The assemblies of apertured members and lenses are identical for eachqof the apertures. I

'Fig. 4 which is 'a face View of the transmitting scanning discl lfi arranged for generating photoelectric currents by scanning continuously moving film records has been described hereinbefore in detail in connection with'the description relating to Fig. 1.1

Fig. 5 shows diagrammatically the arrangement of thetwo groups A and- B of scanning apertures in the transmitting scanning disc. showing'particularly the positioning of different shaped apertures such as round, square and diamond-shaped apertures for half-line stagger scanning. The two groups A and B are positioned for a relative shift of. half a line, the amount stated in describing the arrangement of the apertures in the transmitting scanning disc shown in Fig. 4. The round apertures are shown ashaving a diameter equal to the width of a scanning line and the square apertures ashaving their sides also equalto the width of a scanning ,line. The round and square apertures are posi- ,tioned so that those in the A group are radially displaced as positioned in the scanningdisc with respect to those in the B group one-half the width of their scanning path, and the projected images of the film are advanced as an aperture passes across the scanning field an amount equal to the width of a scanning line. The diamond-shaped apertures may have the same area as the square apertures and are here so shown, as their longitudinal diagonal parallel with the scanningdirection is equal to the length of a side of the square apertures while their radial or transverse diagonal is twice the length of a side of the square aperture. The two groups of diamond-shaped apertures are relatively displaced the same amount as the square apertures and they not only have a fifty per cent area overlap asbetweenithe A and B groups, but also the apertures of each group overlap in the scanning of their image fields. This particular dimension of the diamond-shaped apertures corresponds to The two groups A and B of spirally positioned apertures are located in opposite halves of the scanning disc and are so positioned that the apertures in each half of the disc cause three complete scannings of the field of View, comprising one scanning for each of the three primary color components respectively during each half revolution of the scanning disc. The

apertures in opposite halves of the discpause similar scannings of the field of view but the scanning lines of the alternate scanning cycles are relatively staggered to cause a fifty per cent overlapping of the scanning lines in the alternate scanning cycles. This stagger of the scanning lines is produced by positioning the corresponding apertures in the two halves of the scanning disc with a relative radial displacement equal to one-half the width of the scanning line. This fifty per cent overlap of the scanning lines of the apertures in the two groups A and B causes a relative stagger of the scanning lines in alternate 6, may bearrived at from the following considerations. First, assume that there are six identical spirals of apertures each scanning juxtapositionedlines andeach beginning at the same radial distance from the center of the disc, but

circumferentially displaced by 60 degrees each spiral extending 180 degrees or half way around the disc. Assume that these spirals are numbered l to 6, inclusive, in a clockwise direction.

, for each revolution of the scanning disc.

2 and 5 are moved toward the center of the disc one-third of the radial distance between adjacent apertures in any one spiral, or in other words one-third the width ofca scanning line, and that each of the apertures in spirals 3 and 6 are moved toward the center of the disc two-thirds of such distance. Finally, assume that all of the apertures onthat half of the'discoccupiedby spiral 4 are moved toward the center of the disc onehalf of the radialcdistance between adjacent apertures in any one of the original spirals. The location of the. apertures according to this final assumption is the location of the apertures shown in Fig.6. Each group A and B may consist of one complete 180 degree spiral, namely, spirals I and 4, respectively, and one section of each of four other spirals which are broken as is clearly shown inFig. 6. The portions of thefour broken spirals are the equivalent of two 180 de-' gree spirals, sothat the groupof apertures in each half of the disc comp-rises the equivalent of three complete spirals and completely scans the image field three times during each half revolution of the scanning disc. There are as many diiferent overlapping scanning paths at the receiver as there are apertures in a full spiral multiplied by the number of such spirals; for example, taking 48 apertures in each of the six equivalent full spiralsythey produce an image, in effect, scanned by 288 overlapping scanning lines In the scanning disc 240, the A group maybe considered as commencing with apertures designated A26 IR, AZG IG and 'AZGIB, which apertures are shown entering the area of the field of view 28M, and the B group maybe considered as commencing with apertures designated BZBZR, BZBZG and B2623. The aperture designated AZGIR is the first aperture in ared component spiralythe aperturesdesignated A26IG is the first aperture in the middle third of a green componentspiral, and the aperture designated AZiiIB is the first aperture in the last third of a blue component spiral of the A group ofuapertures. The apertures designated B262R, BZBZG and Next assume that each of the apertures of spirals B262Bloccupy corresponding positions in the B groupofiapiartures. i

Fig. 7 diagrammatically shows the overlapping scanning: paths of the different spirals of apertures in the receiving scanning disc particularly showing the positioning of the different shaped or types of apertures such as round, square and diamond-shaped. In this diagram, one corre sponding aperture, R, B andG, for example the first apertures of each spiral starting in each of the A and B groups for the respective red, blue and green color components is shown for each type of aperture. As heretofore stated corresponding apertures in the different respective color component spirals in both the A and B groups are radially displaced with respect to each other in anyone group one-third the width of a scanning line; and the radial distances of corresponding apertures in the two groups A and B have a difference equaling Que-halfthe width of a scanning line. This all results in a successive overlapping of the scanning paths such that the width of afundamental scanning pathof one aperture is, in effect, divided into six proportionatepaths, in each revolution of the scanning disc causing, in effect, six. times as many scanning lines as there are apertures'in one fullspiral and thus, while employing a comparatively coarse fundamental scanning structure, the appearlines.

, as black and White images.

ance is that of a fine structure with a resolution or fineness of line structure equalling one-sixth that ofthe fundamental line scanning. The general arrangement of the apertures in the several spirals is the same whether round, square, diamond-shaped or other type of apertures are used, as will be obvious from the diagram of Fig. 7.

With the diamond-shaped apertures having the same area as the square apertures, the same amount of light passes through each. When perfectly juxtapositioned square apertures scan an illuminated field of uniform tone, no line structure can bescen but if a television picture isbeing. received, a series of steps will define the edges of oblique lines. The diamond-shaped aperture has the advantage of softening these steps. Throughout this specification, where it is stated that spirals of apertures completely scan the image field, it is to be understood, of course, that the language does not apply strictly to the edges of the field which are, parallel to the scanning This is obvious from Figs. 5 and'l, where the overlapping. of scanning paths is illustrated. The use of such language is justifiable, however, since it departs-from strict accuracy only with respect to a negligible portion of the image field. The electro-optical system as herein described will transmit not only'from the usual Kodacolor filmand produce images in color at the receiving station but it will also transmit, without change in the apparatus, Kodacolor film which has been taken without color filters in the camera and images thereof will be produced at the receiver The system will also transmit from ordinary film which has no lenticular ruling on the film and produce at the receiver black and white images. In each case the regular primary color light sources may be used 7 at the receiver and where blackand white images are produced the colors normally mix to produce white light of the proper tones. This property resulting from the use of ordinary plain film may be used for testing the equipment to ascertain whether the several color channels are balanced. If they are properlybalanced, the pro-' duced images appear in black and white tones and, if out of balance, color distortion. shows.

When this test shows a proper balance of the several channels the equipment is, in such adjustment that images produced in color faithfully represent the natural colors of the object whose image is produced.

In projecting Kodacolor film" the lenticular structure directs the light passing through the three zones on each lenticular semi-cylinder to corresponding zones across the projection lens. These three zones correspond tothe red, green and blue portions of the picture that would otherwise be gathered into a composite whole for that element or strip of picture. The compo nents which represent these colors are registered in black and white tones in the film and if there is no lenticular structure the portions of the picture in and any other element is projected directly through the filter plane but in this system it is there divided upinto three parts. One: part affects the red channel, another part the green channel and a third part the blue channel. When a black and White film is projected, is possible to screen off by an opaque screen, any two of the areas covered by the deflecting prisms and a complete picture will appear at the scanning disc although reduced in brilliancy. When the color factor alone is eliminated and the image'is produced in black and white, this system afiords all of the otheradvantages such as reducing the appearance'of line structure andfiiclcer while employing a relatively coarse fundamental scan ning at the transmitter. However, when the color factor is included as heretofore pointed out while the structure and the flicker period are the same in either case, the addition of color causes a greater blending of the elements and a more pleasing appearance in the produced image.

What is claimed is:

l. The method of reducing in an e1ectro-optically produced image the extraneous pattern superimposed upon the image field by the process of constructing the image strip by strip, which mitted and producing an image thereof strip by strip, proportionately overlapping the respective color component scanning strips in each scanning cycle, and staggering the scanning strips 9. fraction of the width of the scanning strips in alternate scanning cycles.

2. In an electro-optical system, means for pro-- ducing concurrently a plurality of complete images of the same field of view in a common plane said complete images being displaced so as to partially overlap one another, means for scanning an elemental strip across the overlapping portions of said displaced images to produce a beam of light composed of rays emanating at any one instant from an elemental area of said overlapping portions, and means for utilizing groups of rays of said beam which groups corresponding to said respective images for separately producing image currents individual to each image.

3. In combination in an electro-optica1 sys tern, a Kodacolor film having transversely displaced' image components formed on said film, means for illuminating said film, means for projecting images corresponding to said image components by light .controlled by said film on a scanning plane, means for longitudinally relatively displacing the different images, means for simultaneously scanning different elemental areas of said images, and means for simu1taneously generating photoelectric currents representative of the tone values of each of saidscannings.

l. In an electro-optical systeinfor color transmission, a source of light, an optical system for converging light from saidsource on a moving picture lenticular film having the color components: of primary colors of images of objects or scenes, a lens system for directing the light from said film upon a scanning plane, light deflecting means positioned between said-lens system and said scanning plane for shifting the light components of one of the primary color images longitudinally in one direction and the components of another primary color image longitudinally in the opposite direction with respect to said film by substantially one-third the length of the image on said film, a scanning member positioned in the scanning'plane and rapidly scanning successive line areas of the said images, optical means positioned in the path of the scanning beam directing said beam in a given general direction, and separate photoelectric cells positioned in the paths or channels of the scanning beams of the three primary color components of said images formed by the said lenticular film.

5. In an electro-optical system for simultaneously producing a plurality of photoelectric signal currents representative of. the color compo field, means for simultaneously producing on said field a plurality of continuously moving primary color images on said field including means for relatively displacing said images by such an amount as to cause a separation of the lines simultaneously being scanned in the several images by an amount substantially equal to the.

longitudinal dimension of the field of view divided by the number of lines being simultaneously tive primary color light tone components of the image modulated scanning light into respective paths, and light sensitive elements positioned in the said respective paths for generating photoelectric signal currents of the dififerent respective primary color tone components.

6. In an electro-optical system,means for simultaneously producing on a scanning field images comprising the respective primary color components of an object or picture, means for laterally displacing into segregated positions the said respective primary color components, means for producing a scanning phase displacement as between the light tone componentsof the different primary color images comprising longitudinally relatively displacing said images a given amount, an apertured scanning member scanning with a single aperture at any instant an elemental area of each primary color image projected on said field, means for continuously moving said images across the field of view in a direction transverse to the motion of the said scanning aperture, and light sensitive means positioned in the scanning paths of each of the primary color components for generating respective photoelectric signal currents thereof.

'7. A television transmitter comprising an opaque plate having an aperture therein which subtends one frame of a, motion picture film carrying a colored picture record formed by cylindrical lenticulation extending lengthwise of the film, a uniformly continuously moving driving mechanism moving such a film lengthwise past said aperture, a scanning disc having a half circle of apertures on one-half of said discs and lens located between said opaque plate and said scanning disc having its conjugate feel at said film and said. disc respectively and forming an image of said film on said disc, the line structure of said image due to the lenticulations on said film being at right angles to the paths of the scanning apertures across said image, a source: of light, a condensing lens directing light from said source through said film to said projection lens substantially uniformly illuminating that portion of the film which is opposite the aperture in said opaque plate, a first prism deviating the light rays passing through one transverse zone of said projection lens to move the image formed by said rays on the scanning disc approximately onethird the dimension of the image, on the disc from the position where it would have been formed if the rays had not been deviated and in a direction parallel to v the axes of the cylindrical lenticulations on said film, a second prism deviating light rays passing through another transverse zone of said projection lens to move the image formed by said rays on the scanning disc approximately onethird the dimension of the image on the disc from the position where it would have been formed if the rays had not been deviated but in a direction opposite to the movement of the. image by the first prism, a second opaque plate having three apertures corresponding respectively to the two zones mentioned in connection with said first and secondprisms and a third zone of said projection lens, the rays of which are undeviated, a second projection lens adjacent said scanning discs onthe side opposite from said first projection lenswhich gathers the light rays passing through the apertures in said scanning discs from all the zones of said first projection lens and has its conjugate foci at said prisms and second opaque plate respectively formingimages of said three zones at said respective apertures in said second opaque plate, three light sensitive electric devices energized by the light passing through said three apertures respectively in said second opaque plate, and three image current transmission circuits associated with said light sensitive electric devices respectively.

8. The method of reducing in an electro-optically produced image the extraneous pattern superimposed upon the image field by the process of constructing the image strip by strip, which consists in transmitting primary color signal components of the object whose image is transmitted and producing an image thereof strip by strip, proportionately overlapping the respective color component scanning strips in each scan-. 

